Supporters say consumers should know what kind of food they are buying at the grocery store, and genetically engineered fish threaten Oregon's native fish.

Opponents say labeling foods would stigmatize the products, and the engineering process has been proven safe.

"We have a right to know what's in our food," Scott Bates of GMO Free Oregon told the House Agriculture and Natural Resources Committee. He said the technology and the process aren't understood well enough to be sure they pose no health risk to consumers.

But biotechnologist Alison Van Eenennaam told lawmakers that many concerns about genetic modification stem from a misunderstanding or fear of the science behind it.

"The science is not out on the safety of genetically engineered food," she said. "The science is very definitely in."

Van Eenennaam, who has worked on engineering salmon, said it is highly unlikely that genetically engineered salmon would escape and interbreed with Oregon's native fish population. She said genetically engineered Atlantic salmon, which concerns the fishing industry in the Pacific Northwest, is bred sterile and raised in secure tanks in Panama.

Common genetically modified crops include corn, soybeans, canola and cotton. Crops may be altered to resist pesticides, produce extra nutrients or delay spoiling. And biotechnology companies are working to alter food and animals such as apples that stay fresh longer and salmon that grow faster.

Attorney John DiLorenzo said requiring companies to label products violates the First Amendment by compelling speech, and the bills could violate the commerce clause of the U.S. Constitution by favoring the in-state fishing industry over the national biotech industry.

"All we simply want to do is let consumers know what's out there," said Rep. David Gomberg, a Democrat from Otis and sponsor of one bill. "Maybe it's the same way my jacket is labeled whether it's polyester, silk or wool."

From Hawaii to Vermont, states are considering labeling requirements on genetically modified foods, an especially hot topic on the West Coast.

Lawmakers in Washington state are debating a ballot measure that would require labeling on food or seeds made entirely or partly from genetically engineered crops and sold in the state.

Last year, California voters narrowly voted down a similar measure, after a bruising advertising battle between food safety advocates and agricultural and biotechnology companies.

Oregon doesn't have state regulations restricting farmers from growing genetically modified crops, including alfalfa and corn, said Bruce Pokarney, a spokesman for the Oregon Department of Agriculture. Once the U.S. Department of Agriculture approves a genetically engineered product, it is legal to grow and sell, he said.

In Southern Oregon, Jackson County residents will vote on a 2014 ballot measure that would ban genetically modified crops in the county. A proposed Senate bill to give the state authority to regulate seeds would, if passed, pre-empt the measure.

More than 60 countries, including those in the European Union and China, require food labels marking products that have been partly or entirely genetically modified. In the U.S., however, only Alaska has passed such legislation, requiring labels on genetically altered fish and shellfish products.

Advocates of food labeling gained a victory earlier this month when the grocery chain Whole Foods Market announced it would begin labeling all genetically modified food it sells.

The Oregon Legislature will hear several more bills regulating genetically modified seeds, crops and products during this year's session, several of which require food labeling.